For those asking about the code for this, or a public version: it's not easily automatable right now. I'm doing it in a semi-automated way with github.com/jdevoo/nucoll and gephi.org
It's doable in principle, but you would need a Twitter premium API key (standard limits are too strict) and figure out a way to automate the Gephi workflow (prob would need to code this yourself, afaik Gephi doesn't have automation).
I should say, these graphs are easy to make it's just a slight pain. You don't have to be a super hacker. Just get a Twitter API key developer.twitter.com/en.html, run Nucoll, paste your keys, wait an annoying amount of time for it to grab, then load up into Gephi and play with it.
