The Object’s Polygon list contains all of the Polygons that make up the Vector object you selected from the Vector object list. Below left are the polygons that make up the Vector object Car shown on the right:

Tick the box beside the name of the Polygon that you want to change colour. In this illustration, Polygon (10), Polygon (8) and Polygon(6) will change to the colour entered in the New Colour panel when this action is triggered.