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