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