The Paulus graphs are the 15 strongly regular graphs on 25 nodes with parameters 
and the 10 strongly
regular graphs on 26 nodes with parameters 
.
They are implemented in the Wolfram Language as GraphData[
"Paulus", 
n, i
].
The 
-Paulus graph is isomorphic to
the 25-Paley graph.
The 25-node Paulus graphs are cospectral, as are the 26-node Paulus graphs, so none of these is determined by spectrum.
The 
-Paulus graph has the largest possible
graph automorphism group order
of all 26-node Paulus graphs (namely 120), and is sometimes known as the Paulus-Rozenfeld-Thompson
graph (or PRT graph) and denoted 
(Gyürki et al. 2020).
The Paulus graphs are pancyclic.
The 
-,
-, and 
-Paulus graphs have the apparently rather unusual property
of being both integral graphs and identity
graphs.
)
(14 graphs, 7 pairs)." [Excludes the 25-Paley graph.] 
)
(10 graphs)."