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