Create 100 different config files, each of them containing '/name whatever' in a certain colour combination. Since you will most likely not remember which of the 100 config files contains your name in a given colour combination, executing one of them will kind of mimic random colours, since you don't know what to expect.
hmmm as i remember you can add multiple names to one bind. so pushing the button should choose your next name, not a certain one. there you can make the LavaList. holding down the button should even animate your name, creating a spectacular spamwave....
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bind f11 vstr name1
set name1 "name w00t3v4; bind F11 vstr name2"
set name2 "name w00t3v4; bind F11 vstr name3"
set name3 "name w00t3v4; bind F11 vstr name4"
set name4 "name w00t3v4; bind F11 vstr name5"
set name5 "name w00t3v4; bind F11 vstr name1"
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ofc all of this into your cfg.
[EDIT]: note that some servers have limited name changing opportunities, and are flood-protected.