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