The response should contain a "@odata.nextLink" field which can be used to retrieve the next page of the result. An example response could be:
{"@odata.context": "https://graph.microsoft.com/v1.0/$metadata#directoryObjects","@odata.nextLink": "https://graph.microsoft.com/v1.0/users/mytestuser@domain.com/memberOf?$top=5&$skiptoken=X%2744537074090001000000000000000014000000B2B64E48AF94EB439F56F5A33CB75C9301000000000000000000000000000017312E322E3834302E3131333535362E312E342E32333331020000000000011C7FEE5EFEFA46459248691C529273D3%27","value": [ { ... } ... ]}
To retrieve all results we should keep following "@odata.nextLink" of each responses until the response does not contain a "@odata.nextLink" field.