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