This method will create a new Graph that is the transposed version of the original.
At the end of this method the new graph will have all the edges inverted in orientation.
Example: if the graph G contains (V1, V2, V3) as vertex, and (V1->V2, V3->V2) as edges,
the transpose graph G' will contain (V1, V2, V3) as vertex, and (V2->V1, V2->V3) as edges.