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