A vanity slot system is coming to the game in a future patch, but there's no information about when that will be occuring. Until then, a lot of gear can have it's colouring changed via a very simple and easy level 15 quest in Vesper Bay (which requires an orange juice) - doing so unlocks the 'Dye' option on the character screen (which requires a stock of the required dye, a consumable item that can be bought or crafted). It helps break up the monotony of lower level gear all looking the same.