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)(13,14,19,18)(15,20,24,27)(16,17,21,25)(22,23,26,28)(5,7,8,12)(6,9,10,11)(13,15)(14,20)(16,23)(17,26)(18,27)(19,24)(21,28)(22,25)(2,4)(7,12)(9,11)(13,16,18,25,19,21,14,17)(15,22,20,23,24,26,27,28)(6,10)(9,11)(16,21)(17,25)(22,26)(23,28) involution — undirected(13,17,14,21,19,25,18,16)(15,23,27,22,24,28,20,26)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.