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