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