I'd recommend using Grafana. You will have a lot more control over the look and be able to use a separate Y-axis for the switches. I assume you've seen the tutorial.
With the default charting servlet your ON/OFF switch will be plotted on the same scale as your temperatures so will likely be unable see the difference between 0/OFF and 1/ON on a scale that goes to 38 C (100 F) on the chart.
I do something similar, charting the inside temperatures of the three floors of my house with the outside temperature and the on/off state of my house fan and heater. It works great in Grafana.