I don't want to build redisgraph by myself, however I don't find the compiled binary at src/redisgraph.so
The compiled binary is not part of the repository,
you'll have to compile the source code in order to get it,
an alternative would be using the docker image.
You can run the following to get redisgraph.so:
docker create --cidfile /tmp/rg.cid redislabs/redisgraph; docker cp $(cat /tmp/rg.cid):/usr/lib/redis/modules/redisgraph.so .
Most helpful comment
You can run the following to get redisgraph.so: