Small vertex-symmetric Higman graphs with $\mu=6$

Strongly regular graph with $v={m\choose 2}$ and $k=2(m-2)$ is called Higman graph. In Higman graphs the parameter $\mu$ takes values $4, 6, 7$ and $8$. Previously the authors found edge-symmetric Higman graphs.
It is realized the programm classification of vertex-symmetric Higman graphs. In this work we study the vertex-symmetric Higman graphs with $\mu=6$ and $m=9,17$.