When working on my library representing geometric objects, Debugging currently looks like this:
One possible option for you would be downloading the compiled DLL from
Graphics Debugger Visualizer
and decompressing them into your Debugger\Visualizers folder. Somewhere like
C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\Packages\Debugger\Visualizers\
Then restart your visual Studio. As soon soon you start debugging you will see Graphic debugger sign next to the run-time value of the Graphics variable as described in the codeproject solution I mentioned earlier.
Update 1: I also highly recommend you to have a look at the following blog where S.Ullah the author of Custom Visual Studio Visualizer illustrates how to create a visualizer for in memory graphics:
Custom Visual Studio Visualizer
There used to be commercially available product called Mole however it is no longer available for new buyers(I don't know why)