Although the colours may have layers of meaning perhaps related to the story and lore behind each race, I have speculated that the colour of these five cards could be potential markers of the most common eye colour trait found in their populations enough to distinguish them from one another. For example, Race 2 card is blue which represents the Fallen and yet most of them have a blue-eyed appearance so the same logic could still be applied to Race 5 which I assume to mostly have a yellow-eyed appearance and Xur has yellow eyes with a similar stature to the humanoid figure. However, we cannot reach the conclusion that Xur's race is Race 5 since we have not encountered them as of yet but I have a strong feeling they might be so since the pyramid ships are emerging from a planet that looks similar to Rhea, Saturn's moon which is part of the Nine's territory and most of the Nine's iconography involve triangles particularly the tower symbol and Xur's wristband which has streaked triangle figures that may allude to the white clouds as seen in the concept art and the Race 5 card. I must also add that there are exceptions found in each race. For instance, some of the Vex have varying optical colours but ultimately, most of their sects have units with red opticals. In conclusion, Race 5 could potentially be the Nine but we have not encountered them yet to confirm that and the revelation that they are the fifth race does not necessarily mean that they are some unseen evil or ultimately the Darkness that caused the Collapse and they may in fact, be a very strong and powerful ally of Humanity that could assist us in resisting large-scale invasions from forces such as those of the Cabal Empire as hinted in quotes by Xur and the Speaker. Image links for each race:- Vex(Red) :- 1. http://resource.destinywalkthrough.com/library/2014/1413206492e_vex.png 2. http://destiny.bungie.org/galleries/announce_assets/lg/vex.jpg 3. http://www.destinypedia.com/images/d/d9/Grimoire_Virgo_Prohibition.jpg 4. https://www.videogamesartwork.com/sites/default/files/images/image/1418986957/destiny_character_monster_vex_02_additions_04.jpg Fallen(Blue) :- 1. https://s-media-cache-ak0.pinimg.com/originals/a5/1a/20/a51a20af73136b14fc92b3c74edd4b79.jpg 2. https://s.candybanana.com/images/5d16/destiny_213.jpg 3. http://i.ytimg.com/vi/_zOkX9KfZdk/maxresdefault.jpg Cabal(Grey) :- 1. https://electriccartilage.files.wordpress.com/2015/06/face-concept.jpg 2. http://i.imgur.com/AddGMZ5.png 3. http://vignette2.wikia.nocookie.net/destinypedia/images/3/31/Cabal-face.png/revision/latest?cb=20141028052913 Hive(Green) :- 1. http://s1.narvii.com/image/n5ontyq56l24ax72uvg5euredkh25vf5_hq.jpg 2. http://static.gamespot.com/uploads/original/834/8340421/2523122-1139894069-hive_.jpg 3. http://static.gamespot.com/uploads/screen_small/mig/6/1/6/2/2126162-169_destiny_CharacterDevelopment_ot_multi_032813.jpg 4. https://s-media-cache-ak0.pinimg.com/564x/9d/9e/fb/9d9efb26f5d92cbaf12bb2d6272a3184.jpg 5. https://s3.amazonaws.com/destiny-www/assets/article/2016/04/20/Crota-Destiny-Raid_feature.jpg 6. https://assets.vg247.com/current//2015/09/destiny_the_taken_king_oryx_screengrab.jpg Xur(Yellow) :- 1. https://i2.wp.com/planetdestiny.com/wp-content/uploads/2014/07/xur-agent-nine-destiny-exotics.png?resize=660%2C330 2. https://i2.wp.com/planetdestiny.com/wp-content/uploads/2015/03/xur-broken-megaman.png?resize=660%2C330 3. http://static.wixstatic.com/media/e155d7_93228a436bab44c2ae9c2f3fcddcada9.jpg 4. http://static.feber.se/article_images/39/36/57/393657_1920.jpg Additional Image links:- 1.Nine's tower symbol: http://i.imgur.com/HVlDK1n.jpg 2.Xur's arm: http://imgur.com/a/QcHbq 3.Pyramid Ships: https://cdna.artstation.com/p/assets/images/images/001/257/788/large/dorje-bellbrook-db-destiny-194.jpg?1443927684 Link to my previous topic on Rhea: https://www.bungie.net/en-us/Forums/Post/221571895?sort=0&page=0&path=1