Is there a way to determine class of WH space or WH exit to k-space by it's color?
You can't determine where a wh to k-space leads by color, though you can always show info on it to get sec status, but you can generally determine what class of wh a hole leads to by its color. Holes to C1s are blue, to C2s are green, to C3s are yellow, to C4s are orangeish, and then to C5s and 6s are red and black.
What you see in a WH is just the color of the nebula on the other side, and in k-space that's random. For whatever reason it is not completely random in w-space, CCP kind of color-coded WH nebulae by class. I believe there are occasional systems that violate the usual color scheme, but in my experience (and I've spent a lot of time jumping around in w-space) it works.
That said I'll always trust the WH type over the color, when it's not a K162, and either way you should check the info on the hole because there are k-space systems that have the same color nebulae too.