Tree maps are the most compact and intuitive way to visualize cluster analysis findings. But they are very hard to create by hand. Luckily, I found this add-in for Windows Excel that makes them for you! You can also use R, but it is much harder to control the look and feel of the final map than with Excel. Size represents quantity and color represents intensity or some other value scale. Every pixel means something.
I made these tree maps with this add-in from Data Bison (Yes, I paid the $15. TOTALLY worth the hours of time it saved). http://www.databison.com/treemap-add-in-for-excel-demo/
All images are copyright 2015, University of Wisconsin Board of Regents. Used with permission.