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