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