Interestingly enough, Soviet control rooms (https://upload.wikimedia.org/wikipedia/commons/thumb/a/ab/Co...) were the color of Western aircraft cockpits, and vice versa...

While no one would ever navigate by learning what the mosaics mean, it's a fantastic setup for the expected audience of commuters. Give it a month and your brain would associate a given color with your stop coming up soon, and make navigation easier.