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