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