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