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