Guake supports natively 256 colours. And this is the answer to your question ;)
For testing it, you can simply run this script.
Pregunta
Is it possible to make Guake terminal to use 256 colors instead of just 8?
The only info that I found on the internet is this post https://bbs.archlinux.org/viewtopic.php?id=173707 but it didn't work.
Solución
Guake supports natively 256 colours. And this is the answer to your question ;)
For testing it, you can simply run this script.
Otros consejos
Ok fixed: You just need to run this scripts provided here: