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