Is it possible for retinitis pigmentosa and colorblindness to be linked?

Yes. Some types of retinitis pigmentosa (rp) can be linked with a cone dystrophy so you have a bad combination of night blindness, visual field loss and decreased visual acuity and loss of color vision.
No link. These can occur concurrently and advanced retinitis pigmentosa always has a loss of color vision. Classical colorblindness is an inherited disease also, but carried on a different part of the chromosome and is inherited independently of the genes for retinitis pigmentosa. So both can occur together if one inherits both but they are not linked.