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