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