I don't know which version you are using, but I am using the 2007 version.

Insert-Shape-Select Shape-Pull out the shape-Double-click the drawn shape-Fill the shape with the color you want-Select None for the shape outline.

Answer by hand, I hope it will help you. Version 03 is actually similar. After drawing, you can right-click to select and set the graphic format. In fact, it is very simple to explore these.