One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6)(7,10)(8,11)(9,12)(13,14,20,16,19,22,18,25)(15,23,27,28,26,17,21,24)(5,7,10,6)(8,11,9,12)(13,15,18,21,19,26,20,27)(14,17,25,28,22,23,16,24)(2,4)(13,16,20,22,19,25,18,14)(15,24,27,23,26,28,21,17)(5,8,10,9)(6,11,7,12)(13,17,19,23)(14,21,22,27)(15,25,26,16)(18,28,20,24)(5,9,10,8)(6,11,7,12)(13,18,19,20)(14,16,22,25)(15,21,26,27)(17,24,23,28)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.