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