!. Rough it up with steel wool or sandpaper, or apply the blue "glue primer" that's sold for use before gluing. Leave no holidays in the roughing-up, if you want any kind of paint to stick.
2. Paint it with any color of Dupli-Color paint from an auto supply store. It works well on PVC; I've done it often. Maybe use Dupli-Color primer first (after step 1).
3. White is not as good as silver for UV protection. Some white pigments absorb UV, and others don't -- and it's always a mystery what pigment is in the paint you like. Also, it's not always easy to tell how well you covered a white object with white paint. Silver is essential; anyone who has ever covered a fabric-covered airplane (as I have, a wing anyway) can tell you how insistent the makers of aircraft finishes are about using silver. Else the fabric rots from UV, and then you die.
4. What I would do is paint it silver first, because it's easy to tell how good the coverage is (important for UV); then apply whatever color coat you like.
5. For the first coverage (primer or silver), and for every colr change, first spray a thin "mist coat" that doesn't cover very well (you can see through it). Then, after about five minutes, spray a color coat, still not too thick. Thick coats (of any kind of paint) don't adhere well. Also, of course, they run.
I recommend Dupli-Color over Krylon because the quality control for Dupli-Color is really superb. It's good stuff, designed for touchup work on cars, and also the sprayhead produces a nice fan rather than a round fog. Much easier to apply evenly.