Visio allows you to set so-called Themes and Effects for all shapes on a page. Process Modeler comes with some built-in Themes and Effects to help the user recolor and reshape the BPD.
In the Design ribbon, click on the Colors item to apply another color set to your diagram (see picture below). This opens a task pane with a selection of various color schemes. To apply another effect scheme (e.g. to draw all shapes with rounded edges) click on Effects in the Theme ribbon.

A right mouse click on the scheme you would like to apply shows you some options:

• To apply a theme to the drawing on the current page only, right-click a thumbnail, and then click on Apply to Current Page.
• To apply a theme to all pages, right-click a thumbnail, and then click Apply to All Pages.

This will set the Theme to all shapes in your drawing: