Litespeed Web Server v4.1.9 has been released and includes a new rrdtool dependent install script for rrdgraph, rrdgraph_install.sh. Much easier to install than Cacti.
I installed it on this server and ran Loadimpact.com test run with 50 clients ramp up to see rrdgraph in action.
The rrdgraph output from this Loadimpact.com test run. Low load is due to Varnish Cache front end to Litespeed Web server