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