Yes, you can - just make sure its an oil-based candy coloring.
I agree with Beckalita. If you put anything else in your chocolate it will seize up. Always use oil-based candy coloring if you need to color chocolate.
I just made my first CT, and I started with the dark chocolate melts. I added and added and added until my chocolate eventually siezed. After my frustration, and I have to admit, a mini-temper tantrum. I added a little bit of shortening and stirred until it was smooth again, and it worked wonderfully! Perfect black, perfect consistancy.
here, this is what I buy! I LOVE EM!!!
http://www.countrykitchensa.com/catalog/product.aspx?T=2&ShopId=39&CatId=588&SubCatId=571&productId=619028
Or powder coloring. I love that stuff!
How do you use this stuff? I bought a multi pack by Kountry Kitchen (or something like that) and every time I tried to use it, it was grainy. The buttercream had specks in it and when I used it for candy melts, they did too....Is there some secret or trick to using these?
I even tried to use them as a luster dust to brush on color but they didn't work as that either! 
If I just need a small amount, I will use my regular Americolor black and add a pea-sized dollop of Crisco, melt in the microwave and stir. It really helps with the seizing.
I have even used this method to color the white melts black. I never tried it with a large amount, though.
Quote by @%username% on %date%
%body%