Here is a net graph toggle bind that I used to use when I played TFC.
//toggle netgraph
alias ngrfon3 "net_graph 3; net_graphwidth 192; net_graphheight 64; bind h ngrfon1"
alias ngrfon1 "net_graph 1; net_graphwidth 48; net_graphheight 20; bind h ngrffps"
alias ngrffps "net_graph 0; cl_showfps 1; bind h ngrfoff"
alias ngrfoff "cl_showfps 0; bind h ngrfon3"
You can also add net_graph 2 by making the necessary changes, and it also shuts off the net_graph command. I would imagine it would work just as well in NS, but I haven't been bothered to bind it.
**Oh I should add that I got this toggle from the FOOM clan site, and that I know next to nothing about writing binds.