Let $G=Sp(4,2^f)$ with $f>1$. Based on the facts when $f$ is small, I would feel the following:
$G$ has two conjugacy classes of subgroups isomorphic to $SO^+(4,2^f)$. One is in Aschbacher's class C8, and the other is $Sp(2,2^f)\wr2$ in C2. These two classes of subgroups are swapped by the graph automorphism of $G$.
Is this right and where can I find the related stuff? Thanks!