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