Would you provide your system information as requested here https://github.com/ValveSoftware/steam-for-linux#reporting-issues
Yes, sorry, my bad. There.
Not just random colors:
It actually shows textures from the overlay. I've had it pop up images from it. This has also happened in Osmos and Aquaria, come to think about it.
This is most likely a problem with your video drivers.
Hm... It would seem that. Can anyone running Catalyst confirm this doesn't happen?
http://steamcommunity.com/app/221410/discussions/1/882966056439870495/
So I've found that, which means it's a Mesa issue as it also happens on Intel drivers.
Nothing extracted yet.
I'm on Arch Linux 64bit and I get this kind of error when I switch to steam overlay, to chat with friends: