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)(15,19)(16,24)(17,21)(18,22)(20,23)(25,27)(26,28) involution — undirected(1,2)(3,4)(5,7)(6,10)(8,11)(9,12)(13,15,18,17)(14,19,22,21)(16,23,25,26)(20,27,28,24)(2,4)(13,16,18,25)(14,20,22,28)(15,23,17,26)(19,27,21,24)(6,11)(7,12)(14,21)(15,17)(19,22)(20,24)(23,26)(27,28) involution — undirected(5,8,9,10)(6,7,11,12)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.