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