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