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