Hi David,
This could be achieved by using SelectedColorGroup property of the ColorPickerButton.ColorUI object.
Here is the code snippet:
this.colorPickerButton1.ColorUI.SelectedColorGroup = Syncfusion.Windows.Forms.ColorUISelectedGroup.CustomColors;
Herewith I have attached the sample. Please have a look at the sample and let me know if it helps.
ColorPickerButtonThanks for choosing Syncfusion products.
Regards,
Murugan P.S