There's an old mod made by Jeffrey Alexander for the original X-Com that I've been using successfully for years and would love to see in Openxcom as well, like some other classical mods already in the game.
This mod contains multiple colour schemes for each vanilla armour and automatically matches it to the terrain, so for example if you go to a desert, you get a desert camo.
Naturally this would require additional code, so I'm just leaving it here for talented people who could want to give it a try. (Seriously, it's a cool feature.)