I'm guessing you were told to use either vinylester or epoxy resin for the repair. On your inquiry about paint, I may be able to help. I'm not a fiberglass pool builder but I have been in the boat mfg and repair business for almost thirty years. I don't know if there is a "paint" available to the pool industry but you could use gelcoat to color the surface. Gelcoat is basically a colored resin. If you don't already know, the pool you are trying to repair has gelcoat on it already. It's the colored surface that you see.
Gelcoat is a two part resin based system much like the resin you are using to repair the crack. If you are using vinylester resin, you already have one component of the mix, MEKP, the catalyst for the resin. It is used with gelcoat to harden the mixture. If you are using epoxy to make the repair, then you'd need to buy the MEKP as well as the gelcoat.
Minicraft of Florida sells gelcoat in quantities as small as one pint (at least I think one pint is the smallest). They have stock colors as well as the ability to match any color you choose. I believe their website also has some instructional info about using gelcoat. Here is a link to Minicraft: http://www.minicraft.com//index.html
If you have any specific questions about the repair or gelcoat application, you can shoot me an email. My email is
[email protected]