Trimerotropis [verruculatus] suffusa. It looks like a female in it's last (5th) instar, and would mature to look about like this one:
.

T. [cyaneipennis] fratercula is very closely related (I think they sometimes hybridize), but it is usually lighter in color (though yours is pretty light for T. suffusa); I think the edges of the top of the pronotum usually aren't as sharply defined; and, it would not likely turn up much above 7000 ft (perhaps exceptionally 8000). It is usually found in the "Upper Sonoran", and if associated with trees, they are usually Juniper, Piñon, or occasionally Ponderosa Pine. It likes dry rocky slopes in the "foothills", and is abundant in places like the slopes around Colorado Springs, Salida, and Trinidad, and is spotty all along the base of the Front Range (becoming rare north of about Castle Rock). It is also on exposed limestone bluffs with Limber Pine and Juniper out in the Pawnee Buttes area in Weld and Logan Counties on the Plains. If it's in Park County, it would only be at the lowest elevations in the south end of the county.

T. suffusa is common throughout the mountains, usually higher up, and is in a wide variety of open dryish sunny places, but most often near or under trees, sometimes flat, sometimes sloping or on hilltops. It is has a proclivity for colonizing mountain camp grounds and abandoned gravel forest roads. It becomes rare below about 7000 ft. in the south and 6000 ft in the north of Colorado.

The other species I was considering is T. cincta, but I don't think that's what you've got here.

Moved from Trimerotropini.

[that or perhaps Circotettix] - a last instar nymph. I can probably figure out the species with a bit more time. What was the habitat like? That could help.

Moved from ID Request.