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