Hello Randy,
Contemporary advertising lithographs reproduced in the book, The Sunset Limited, show the 1897 Sunset cars in olive green with brown vestibule doors and window sash, and gold lettering and striping. The trucks were also olive green and striped, and the paper wheel centers are shown in dark brown. (The outer faces of the paper wheels were actually iron or steel plates.) The roofs were probably black, except that the clerestory sections are shown as green like the sides.
While only a few pages of this book deal with these cars, it does have several exterior and interior photos and would be valuable to anyone modeling this train. It's avaialble from the SP Historical & Technical Society at sphts.org.
Good luck with your train,
Andy