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