Hi MelodeeB,
As far as I know there is no expand or collapse options for shapes in Visio 2013. L
And I find an article you can read. This article is about how to set nodes in Visio, I suppose this can be a workaround for you:
http://blog.bvisual.net/2012/07/11/selecting-nodes-in-visio-pivotdiagrams/
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
There is a detailed steps and sample in this article, please check if it works for you. Im glad to help you.
Hope its helpful.
Regards,
George ZhaoTechNet Community Support