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