I played this game for the first time on Monday. One of our players is colour blind and found it difficult to distinguish between the colours on the building cards to make use of the character powers.AFAIK, it should be obvious enough to figure out the color of a district based on the context. However, I'm biased since I've played enough that I already memorized the colors anyways. Alternatively...
It would have been useful if the number of the character that gained an advantage from the colour (e.g. Warlord/Red) was placed on the card or (if that is not possible due to the other character cards ... we only played with the basic set) then an icon/shape on the building card and the character card would have been useful.
1) print this out and give it to him as a reference
2) use a sharpie to mark the front of the cards. I've seen copy of Race For The Galaxy and Taj Mahal that did this, and it did help out alot....
R for red
Y for yellow
G for green
B for blue
P for purple