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