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