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