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