To turn the graph taskbar extension on, right-click an empty space on the task bar and choose Toolbars - NetWorx Desk Band. If NetWorx Desk Band is not shown in the list of tools, reinstallation of NetWorx might help.
You may also need to unlock the taskbar to resize the graph. To do so, right-click an empty space on the task bar again, untick the Lock the taskbar menu item, resize the graph to the size you like, and then lock the taskbar again.