An example of folders structure for Express + GraphQL

|-- structure
    |-- .gitignore
    |-- package.json
    |-- ...
    |-- src
        |-- server
            |-- index.js
            |-- middlewares
                |-- graphql
                    |-- schema.js
                    |-- mutations
                    |   |-- mutation.js
                    |   |-- index.js
                    |-- queries
                    |   |-- index.js
                    |   |-- viewer
                    |       |-- index.js
                    |       |-- queries
                    |           |-- list
                    |               |-- index.js
                    |-- types
                        |-- type.js

An example of code in folders you can reach in this repository.