There are only 18 colors in the palette. The only way I can think of is to avoid repeating colors is to assign a unique color to every dimension value in the load and then a reference to that color in the background color expression.
Alternatively, you could get a better distribution across 18 colors with an expression that uses some combination of index() and concat() to sequentially assign from the 18 color palette.
However, I would question the overall usefulness of having a Pie with some many slices. Have you considered using Dimension limits to limit to the top n values and throw the rest into the "Others" bucket?
Rob i have only 10 segments as shown in the above image... i want to show these 10 segments without repeating the colors and i really would prefer if i could change this color code and make it more professional is it possible??
I feel like I'm missing something. You shouldn't have repeating colors if your underlying data has less than 18 values, but maybe I'm misunderstanding something. It would be easier if you could share a scrambled version of your app. Anyways, here's an expression (getting complex though) that will distribute any values over the 18 colors.