Graphql library helper to connect to external endpoint

For a project I have to do some requests in PHP to a GraphQL endpoint. I’m familiar with Graphql to build query’s. The most of the project is build in node.js, where I use axios to handle the requests.

But in PHP I couldn’t figure it out, it seems I’m having problems setting up the request (correct URL construction, sending headers, ..).

I’m looking for a library / helper that can connect an external GraphQL Server or an example how to build this in PHP properly.

Most of the thing on the internet I found is to create an own graphql server, but this is not what I want. I really need to contact the external server.

Things I tried/found:
Library Graphql-php: https://github.com/webonyx/graphql-php (didn’t found how to use it for an external server)
File_get_context

Some that can help me?