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