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