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