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