To install the graphs, you have to run J Prochazka's automated install script.
Automated Installation of Dump1090-Mutability, Data-Feeders, and Performance Graphs
When the script starts, it will offer you lot of options. As you have already installed everythimg else, just do NOT accept offer to install or upgrade anything, and continue forward, till it offers "Web Portal". Accept the Web Portal installation, as graphs are part of the Web Poetal. Also in web portal installation, say NO to "Advance Options"