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