As its name suggests, the Denver & Salt Lake was trying to build from Denver to Salt Lake City, but only made it as far as Craig, Colorado. The dream of a Denver-Salt Lake route was realized when the Denver & Rio Grande Western built the Dotsero cutoff, and later acquired the D&SL. That left the line to Craig orphaned, but until 1967 the D&RGW continued to provide passenger service on that branch.
Originally called the Yampa Valley Mail, it became the Yampa Valley when the Post Office terminated the mail contract in 1963. However, the train often carried a dome car, which made it popular among rail fans.
I’m unable to replicate the orange color of this brochure. As shown, the orange looks very much like the Rio Grande Gold used on passenger trains. But the brochure itself is printed in what appears to be DayGlo or florescent orange, which can’t be reproduced on screen or on an ordinary printer. Since you can’t find the color on line, you’ll just have to use your imagination.