Good to see other people interested in SynBio.
Here is a somewhat outdated list of synthetic biologists in the US: http://syntheticbiology.org/Labs.html
I think only Rice has a graduate program that specifically mentions synthetic biology in the program name
For other schools, professors working on synthetic biology are in bioengineering, biomedical science, chemical engineering departments. Usually, synbio professors represent multiple departments.
As FLAGtagSwag has mentioned, if you are interested definitely think about applying to UC Berkeley and UC San Francisco.
I think Boston University has good reputation in synthetic biology (but James Collins left BU to MIT, so this might change)