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