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