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