"blueorangepink" works.

I found it by typing in a random password, then using as a password the colors from that password, and repeating until I got the self-referential password. I can't think of a good reason why this should work, though. And you might argue that the third color there is really purple, not pink.

New question: lots of countries have flags which consist of three stripes. Is there a country whose chromahash is its flag?

"multicoloured" :-)

Not to just be a smart-ass, I tried a few others, but couldn't find any that worked well.

startpinkendgreen

Still trying to find one for all three colours. (This is fun! :P)

Some close ones: "same", "differentgreens".

"wildblueyonder" produces a blue bar on the far right.

"wild blue yonder" produces two blue bars on the left.

"orangegreen"