Base on AEM release notesGraphQL is available from AEM 6.5.10. So first you will have to upgrade your instance, and as a next step install GraphiQL. Please be aware that on AEM 6.5.x GraphiQL is available under /content/graphiql.html and may not be available directly as an option in the menu- of course first you have to install GraphiQL Content Package.
You can also have a look on this article that describes step by step how to configure it:
Base on AEM release notesGraphQL is available from AEM 6.5.10. So first you will have to upgrade your instance, and as a next step install GraphiQL. Please be aware that on AEM 6.5.x GraphiQL is available under /content/graphiql.html and may not be available directly as an option in the menu- of course first you have to install GraphiQL Content Package.
You can also have a look on this article that describes step by step how to configure it:
As you said the option is not available on the menu, but going directly to the url http://localhost:4502/content/graphiql.html is goin fine but I can't see the dropdown to select the endpoint and the option to save queries.