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