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