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