To access Microsoft Graph, Microsoft provides Graph Explorer. It's a free and open source tool that allows developers a nice way to query the Graph APIs. You can download the code from https://developer.microsoft.com/en-us/graph/graph-explorer if you want to see how it works but there's no need for that because you can just use the tool at https://graph.microsoft.io.
You can use the tool with sample data, or you can log in with your Microsoft or Organizational account to get full benefits. This way, you can query against live data. Just be careful as the data is yours and you could accidentally modify or delete critical items.
Queries against Graph API can be entered in the query bar, in the form of https://graph.microsoft.com/{version}/{target}. The version at the time of writing this book is either 1.0 (for stable endpoints) or beta (for upcoming features). Typically, you would call Graph APIs through https://graph.microsoft.com...
