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