Will this step be used for anything other than plotting?  As it stands, you're extracting an invalid subgraph, right?  Meaning you have dangling edges?

If we can't think of a use for this step outside of plotting, then let's roll the PLOT_GRAPH and this step into one step with the startSeed and numHops as optional values (so the SHOW_GRAPH would run on the entire graph if you don't specify the seed).