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