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