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