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