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