Science is often associated with graphs and equations. Graphs are a nice way to show a scientific result or the basis of a scientific conclusion. If carried out nicely, it can enhance understanding in the audience and support your scientific message.
The rule of thumb for inclusion of graphs is to ask if the graph is intuitive. Will a person with non-scientific background be able to understand the graph without too much information? As subject matter expert it can be risky to use graphs that are very familiar to yourself, because you can overestimate what the audience is capable of understanding within the framework of your science communication.
Should you choose to include a graph make sure to keep the resolution high, the colors sharp and the graph intuitive. Be careful not to use for instance yellow and orange next to each other. They might look distinguishable on your screen, but when blown up on a projector, they can easily look so similar that the audience can not tell the difference.
Lastly, make sure there is a specific message related to the graph. A conclusion or measurement or something in that ballpark. After the audience have seen the graph they should be able to re-tell what the point of the graph was.