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