The demo model vr_octavia_graphs.mdl is for the Simulink 3D Animation Toolbox. http://www.mathworks.com/help/toolbox/sl3d/f2-35107.html#bsns2w2-1
I don't think TMW provides a weblink to download a particular demo model. But if you are really interested in the model and the related toolbox, you can get a trial version of the toolbox at http://www.mathworks.com/products/3d-animation/tryit.html. The demo model must come with it.
Be cautious though, that if your current MATLAB/Simulink is an older version, you may have difficulties open the model or see the full capability of the model.
