A three color crayon
In 2007 Crayola sold a set of eight True to Life crayons. Each was extra long, came in a plastic case and mixed three colors. Grand Canyon combined a dark reddish brown, #6D3834, with a dusty red, #B36058, and black. Those codes are rough guesses listed in the Wikipedia list of Crayola colors.
The #A05D4D on this page lies between the two main crayon colors. It comes from an open online name list, not from Crayola. On this site it is very close to redwood.
The red tone fits the real place. One of the canyon's main rock layers, the Redwall Limestone, was named for the red color of its cliffs.

