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