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)(14,18)(15,21)(19,25)(22,23)(5,6)(7,10)(8,12)(9,11)(14,19)(15,22)(17,24)(18,25)(20,26)(21,23) involution — undirected(2,4)(13,14,16,18)(15,20,21,26)(17,25,24,19)(22,28,23,27)(5,7,9,8)(6,10,11,12)(14,18)(19,25)(20,26)(27,28)(5,8,9,7)(6,10,11,12)(13,15,16,21)(14,20,18,26)(17,22,24,23)(19,27,25,28)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.