BuildGraph is implemented as part of AutomationTool, which you can run directly from the Unreal Engine 4 solution on Windows,
or via the
Engine/Build/BatchFiles/RunUAT.bat batch file from the command line. On Mac or Linux, it can be run with the
Engine/Build/BatchFiles/RunUAT.sh shell script. If you'd like to get an idea of how to use BuildGraph from the command line,
we've written sample usage commands for your reference.