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