Even though cow punchers would be dirty and dusty after their trek they would have pockets full of cash to spend. It needs a fancy paint job! And lots of bath tubs!
Well, here is Deadwood, KS in the 1880’s, at the other end of the cattle trail.
Here’s the 7th Cavalry, in 1890. I just had to throw this one in. 
If you are modeling the 1880’s, a repetitively prosperous time, most buildings had paint. If you are modeling the 1930s, the paint might be peeling, but the building would still have color.
i did a little web search.
if i am not misstaken, the mining and logging towns were mostly unpainted.
but the other “western” towns seem to have been mostly painted.
adding the thought, that the lower level of my layout (2 1/2 foot to 5 foot height) receives less light, than the upper level, i think, i should build this town with most buildings painted.
(adding some outhouses and sheds showing weathered wood)
so at the moment i am thinking about a somewhat “aged” white, with window and door frames in a dark green (to go with the name “Greenback”)
seems, that further investigation and testing will be needed.
edit - i am astonished, how widespread the cavalry had their camp.
done (the thread, not the model) - as far as possible. 
here is the (first ) follow-up of this speedmodeling: