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