Nisquallia olympica females range in color from dark slate gray through lighter gray, mottled brown, olive and rust. Some of the color variation may be related to how recently they’ve molted.
Image 6 shows the ventral side of a female, shot through the wall of a plastic terrarium.
“Two New Melanoploid Genera (Orthoptera: Acrididae: Cyrtacanthacridinae) from the Western United States” James A. G. Rehn, Transactions of the American Entomological Society (1890-), Vol. 78, No. 2 (Jun., 1952), pp. 101-115. (See JSTOR link Available to read onlline with a free account.)Jacques R. Helfer, How to Know the Grasshoppers, Crickets, Cockroaches and Their Allies, Wm. C. Brown, 1963 (republished in 1987 by Dover)