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