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