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