The cars were originally painted as you saw. The entire coach project was performed by the Commission and the cars were built with contract labor, supervised by the Commission. At the time the cars were under construction, the commission was busy ousting Scenic Rys and hiring Kyle, so there was absolutely no input from the real railroaders in the design - which is why they look the way they do.
The cars went into service in 1982 and ran with that paint job until around 1986. At that time, the next generation of cars were being built, designed by us, built by us and painted by us in traditional Pullman green. It was decided to repaint all the passenger fleet the same color, so the first generation got painted green to match. At the time we segregated to two trains equipment and I thought it would be nice to paint the Chama train Pullman Green and the Antonito train Tuscan Red, figuring the flat roof cars would look better in that color and at Osier we could simply tell the passengers to get on the "Red Train" for Antonito and the "Green Train" for Chama. I think we went with green because we already had the paint in hand.