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