If you are simultaneously working with the GraphViewer and the Statistical Viewer, you can easily switch between these two views using the shortcut icons in the lower left corner of both windows.
However, the two windows have also been designed to communicate with each other. The corpus graph currently displayed in the GraphViewer will be displayed and marked in the Statistical Viewer if you select the Display in Statistics item of the GraphViewer's context menu (activated by pressing the right mouse button in the GraphViewer panel).