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