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