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