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