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