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