Purple Owl's Clover (Castilleja exserta) - more pics at Bay Area Hikers
The Mt Diablo flower book says it isn't a clover at all and is closely related to paintbrushes. You'll see them near Deer Flat and Devil's Elbow as well as along Burma Rd and Pine Creek.
This photo (from the above site) was take at Black Diamond. BTW, the color in Thom's photo is much closer to the photo in the book. Since the color of your bike looks very true, I'm guessing his photo has the better color (but then we knew that it would).