Phil,
I checked with Stan Piteau, about the colors. I thought he would be the best person to ask. He has a lot of information on Culver production and history.
He says that he has found only one reference to color in all of his Culver documents. That one was for a plane to be delivered to the customer wearing yellow paint, with the trim color to be applied later.
All of the old photos are black and white, but at least you can get an idea of the paint schemes that were used.