Visio is packaged with dozens of stencils containing simple or complex shapes that you can use to produce drawings of various types.
The TaskMap Stencil includes six TaskMap shapes that were designed by Harvard Computing Group, Inc., specifically to produce TaskMaps.
The following is an image of the TaskMap Stencil arranged horizontally.

If you hover the mouse over any of the TaskMap shapes in your stencil, descriptive text about the shape will appear as shown above for the Task Link.
Positioning the Stencil
You can position the TaskMap Stencil window in a variety of ways. You can make it float over the drawing page, or you can dock it at the top, bottom or side of the workspace. In any of those locations you can alter the size and shape of the stencil pane to fit your needs.
For drawing TaskMaps, many people find it convenient to make the stencil tall and thin and then dock it on the left side of the workspace as shown in the picture below.