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