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