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