One vertex per element, one color per generator, with an edge from x to x·s.
(5,6)(7,10)(8,12)(9,11)(13,14)(15,23)(16,19)(17,20)(18,27)(21,24)(22,25)(26,28) involution — undirected(1,2)(3,4)(5,7,9,8)(6,10,11,12)(14,19)(15,18)(16,25)(20,28)(21,27)(22,23)(24,26)(2,4)(5,8,9,7)(6,10,11,12)(14,20)(19,28)(21,22)(23,27)(13,15)(14,21)(17,18)(19,23)(20,22)(24,25)(27,28) 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.