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