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