def METHOD_NAME(self, context, layout):
    col = layout.column(align=True)
    row = col.row(align=True)
    row.prop(self, 'color_start', text='')
    row.prop(self, 'color_end', text='')
    row.prop(self, 'show_options', text='', icon='SETTINGS')
    if self.show_options:
        row = col.row(align=True)
        row.prop(self, 'simple', toggle=True)
        row.prop(self, 'grid', toggle=True)
        row.prop(self, 'plane', toggle=True)
        row = col.row(align=True)
        row.prop(self, 'alpha')