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