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