Hello!
Default PieChart slice colors are as follows:
[ "#2fc32f", "#b0dc0b", "#eab404", "#de672c", "#ec2e2e", "#d5429b", "#6f52b8", "#1c7cd5", "#56b9f7", "#0ae8eb" ]
You can change these here:
https://zoomcharts.com/developers/en/pie-chart/api-reference/settings/pie/style.html#doc_sliceColors
In case you want to change slice color for some exact slices, then you can use slice.styleFunction()
And here is an example:
https://jsfiddle.net/artursr/m2hjrmvb/1/