Folks will need a bit more information in order to give you a reasonable answer. What kind of data? How much? Do you need to migrate data in an ongoing way via stream, or one-time by batch so you can shut off elasticsearch? What graph model are you migrating into? What other technologies do you have around that you know how to use?
For starters, you should check the APOC integration with Elasticsearch as a source of ideas.
https://neo4j-contrib.github.io/neo4j-apoc-procedures/3.5/database-integration/elasticsearch/
