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)(15,24)(16,21)(17,22)(18,23)(19,25)(20,26)(27,28) involution — undirected(2,4)(5,7)(6,9)(8,11)(10,12)(13,15)(14,19)(16,26)(17,25)(18,27)(20,23)(21,24)(22,28) involution — undirected(7,11)(9,12)(13,15)(14,20)(16,26)(17,25)(18,27)(19,23)(21,28)(22,24) involution — undirected(7,11)(9,12)(13,16,18,17)(14,21,23,22)(15,25,27,26)(19,28,20,24)(6,10)(9,12)(13,16,18,17)(14,21,23,22)(15,26,27,25)(19,24,20,28)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.