Use this if you are using igraph from R
isomorphisms {igraph}  R Documentation 
Calculate all isomorphic mappings between the vertices of two graphs
isomorphisms(graph1, graph2, method = "vf2", ...)
graph1 
The first graph. 
graph2 
The second graph. 
method 
Currently only ‘vf2’ is supported, see

... 
Extra arguments, passed to the various methods. 
A list of vertex sequences, corresponding to all mappings from the first graph to the second.
Other graph isomorphism:
count_isomorphisms()
,
count_subgraph_isomorphisms()
,
graph_from_isomorphism_class()
,
isomorphic()
,
isomorphism_class()
,
subgraph_isomorphic()
,
subgraph_isomorphisms()