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