Monitor incoming TCP/UDP flood attack and graph it

I'm preparing a presentation on a security issue and want to include a demonstration. It won't be in real time, I just need to show some pictures of the results.

I have some VPSes that will perform a tcp or udp flood attack simiultanesly on another specific server (Debian/Ubuntu), all of them owned by me of course. Something like a tiny scale DDoS attack.

I want some suggestions for existing tools or new programs to be installed on the target server (Debian/Ubuntu server distro) that can monitor and produce traffic graphs and related charts so I can present the network state before and after the attack.

I don't want to mitigate or stop the attack, but to show the results of it and if possible in a fancy way.

I'd appreciate every idea and suggestion, thanks.