I repainted my bumper about a year ago and ran into the same issue. The bumper paint code is not listed on the sticker (DS door jamb). Instead, I just took the paint shop's book out into the light next to the bumper and compared swatches until I found the Toyota color that matched. Surprisingly, Toyota must have over a dozen shades of gray that come very close to the bumper color. The good news is that I can't tell the difference between the old bumper color and the new, so I must have hit the right one.
If you don't get an answer here, I'll take a look at the paint can and see what they used and post it later.