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