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