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