Assigning colour to surface/geometry based on its orientation

Hi,
I'm needing to know of a solution or method of being able to Assign 4 different colours to different individual elements/surfaces in my model based on orientation. The idea would be to assign 4 colours to 4 different derections ( North, South , East, west). I've thought that it would be possibly do assign each colour to a particular degree range on the X,Y plane for example 235-45 degrees would represent North/ red, 45-135degrees East/green and so forth.

If anyone can please give me some assistance in generating a script or have a script that will work that would be great.

Thanks