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