Are these graphs isomorphic? construction of map.

Question

Both of these graphs have 8 vertices, each with degree 5 and they have 20 edges. They seem to be isomorphic, but I am unable to construct a map between these graphs.

Answer 1

Consider the complement of each graph. The first is $2 \times C_4$ and the second is $C_8$. So they are not isomorphic. (Where $C_n$ is a cycle of $n$ vertices).