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