Jackie, you can either create your own custom color palette, or you can use the cyclic palette, or you can just double-click each of the marks in the edit color box and assign it whatever color you want, essentially creating a custom color palette on the fly.
Or you can do what I did and download and use Michael's awesome color palette!
It's probably hard to discern because there are too many colors. Try to use color sparingly and if you need to see all 48 categories maybe try sparklines?
Yeah, there's no way you're going to be easily able to pick out a color among 47 others - with at least a few being very similar. What are you trying to demonstrate on the chart?