The CBCGPChartSeriesColorTheme is an internal class manages series colors, which are generated automatically for each theme (CBCGPChartTheme).
Currently there are 5 basic colors, that are assigned to series. If a diagram displays more than 5 series, this class builds additional colors from the basic colors.
Please refer BCGPChartExample (BCGPChartExample.cpp, methods SetupCustomColorTheme and InitSeriesColors) for more information about custom color themes.