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)(15,20)(16,26)(17,22)(18,23)(19,21)(24,28)(25,27) involution — undirected(1,2,4,3)(5,7)(6,9)(8,11)(10,12)(13,15,18,24)(14,20,23,28)(16,25,19,17)(21,22,26,27)(6,10)(7,11)(13,16,18,19)(14,21,23,26)(15,17,24,25)(20,27,28,22)(6,10)(9,12)(13,17,19,15,18,25,16,24)(14,22,21,20,23,27,26,28)(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.