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