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