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