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