One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,3)(6,10)(11,12)(16,24)(20,25)(23,27)(26,28)(5,6)(7,11)(8,12)(9,10)(14,18)(15,21)(20,25)(23,27) involution — undirected(2,3)(5,7,9,8)(6,11,10,12)(13,14)(15,22)(16,20)(17,18)(19,21)(23,28)(24,25)(26,27)(1,3,4,2)(5,8,9,7)(6,12,10,11)(13,15)(14,19)(16,23)(17,21)(18,22)(20,26)(24,27)(25,28)(13,16)(14,20)(15,23)(17,24)(18,25)(19,26)(21,27)(22,28) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.