As with pretty much all controls and objects in Visual C++, the graph is a window that inherits from CWnd. So, it inherits all the CWnd functionality (such as the ability to hide and display). You can hide the window and display it the same way you would with any window.
m_Graph.ShowWindow(SW_HIDE); //to hide graph
m_Graph.ShowWindow(SW_SHOW); //to show graph
Best Regards,
Chris Matthews
National Instruments