Take the suttle bus on Zion Canyon Scenic Drive to "Weeping Rock". Spring and early summer is the best time to see the colors.
I shot this small section (with the six foot gray/black rock on the left, having a hint of blue) using my 60mm f/2.8 Macro lens; speed 1/4 second; aperture 11.0; IOS 100. When I opened my shot in its raw format, I was pleased with the colors I was able to bring out -- even though this shot was taken in late October.
"Weeping Rock" is a beautiful place to see natures colors. It is a quarter mile walk from the parking lot to the rock wall where the water and plant life are abundant in the spring and summer.