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