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