It is definitely possible. As you know, leaving almost anything out in the sun for an extended period of time will fade (clothes, couch cushions, stuffed animals). For the pools, it really depends on the printing method that was used to apply the color or design. To help preserve the color and design of the pool, you should bring it inside or into the shade when it is not being used. Part of the beauty of these small pools is the fact that they are small, easy to fill, easy to empty, and easy to move.
Also, keep in mind that while the color or design might impress your children at first, they will learn to love this pool no matter how it looks. Think about how children are with their stuffed animals. They can lose an eye and have stuffing falling out of the armpit and the kids will still want to sleep with it.