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