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