Graph essentially consistes Vertex, Edge and Triplet, each is an implementation of RDD, therefore, methods that are applied to a RDD can be applied to Vertex RDD, Edge RDD and Triplet RDD. If you want, for example, you can convert Vetex RDD, Edge RDD and Triplet RDD to Spark SQL dataframe and use SQL to manipulate them.
Vetex, Edge and Triplet
Vertex is a 2 element tuple: (vertex id, attribute)