And what about: What is the colour like?
yeah, i thought that's what this one would be :/
That is Jaká je TA barva.
why jaka and not co?
You are asking which or what kind of. It can be said in English also using "What", but that does not mean the same can be done in Czech.
"Which color is it?"
Why it is not correct?
It is now.
And what do you say if you mean "How is the color?", that is, you're asking someone's opinion about your choice of color?
You would have to say 'how do you like the color' Jak se ti ta barva libí?