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