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