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