SmartDraw lets you connect to your Github account so you can generate a class diagram using a built-in data visualizer.
You can access these built-in data visualizers from the Insert Content view (under the Plus + menu in the left bar).
Select the Add Data Visualizer section and click on Class Diagram. You'll be given the option to connect to Github from the visualizer.
Learn more about connecting to Github through the Class Diagram visualizer.