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)(13,14,18,20,19,15,17,22)(16,24,26,21,27,28,25,23)(2,4)(6,9)(10,12)(14,20)(15,22)(17,18)(21,24)(23,28)(25,26) involution — undirected(2,4)(13,15)(14,19)(16,23)(17,22)(18,20)(21,27)(24,25)(26,28) involution — undirected(5,7,8,11)(6,10,9,12)(13,16)(14,21)(15,23)(17,26)(18,25)(19,27)(20,24)(22,28)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.