By default, only admin users (those with the manage_options capability) have access to the different screens of plugin Gato GraphQL in the admin.
This extension Schema Editing Access enables to grant non-admin users access to the GraphiQL and Interactive schema clients in the admin, and to read and/or write the different Custom Post Types from this plugin:
Access Control Lists
Cache Control Lists
This is achieved via two different methods:
By assigning the custom capability manage_graphql_schema to the user
By selecting the user roles that can edit the schema (down to the "Author" level)