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