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