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