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