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