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