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