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)(15,23)(16,22)(17,21)(18,20)(19,26)(24,27)(25,28) involution — undirected(2,3)(6,9)(10,12)(13,15)(14,19)(16,25)(17,26)(18,24)(20,28)(21,23)(22,27) involution — undirected(1,2,4,3)(5,7,8,11)(6,10,9,12)(13,16,17,18)(14,20,21,22)(15,24,26,25)(19,27,23,28)(1,3,4,2)(14,21)(15,24)(16,18)(19,27)(23,28)(25,26)(6,9)(10,12)(13,16,17,18)(14,22,21,20)(15,25,26,24)(19,27,23,28)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.