Well, just configure a dashboard with your series. What’s your problem exactly?
BTW, it looks like Graphite is more or less dead… If you don’t already have a strong commitment to Graphite, I advice you switch to InfluxDB (that supports the Graphite protocol) and Grafana.
You don’t get it right.
StatsD is a tool for computing metrics and possibly store them in Graphite.
Gatling computes its own metrics, it has no use for StatsD, it directly pushes to Graphite (Carbon, strictly speaking) (or InfluxDB).
Then, you have to create your own dashboard in the web interface and select the metrics you want to display.
Check our documentation: http://gatling.io/docs/2.1.2/realtime_monitoring/index.html