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