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 (26, 10, 3, 4).
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
(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)."