One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,17)(12,15)(13,16)(14,19)(18,23)(20,22)(21,24)(27,33)(28,36)(30,38)(32,39)(34,40)(35,37) involution — undirected(1,2)(3,7)(4,8)(5,6)(9,11)(10,14)(12,18)(13,19)(15,21)(16,17)(20,24)(22,23)(25,26,29,31)(27,34,35,30)(28,32,36,39)(33,40,37,38)(2,6)(7,8)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,27,29,35)(26,30,31,34)(28,37,36,33)(32,40,39,38)(1,3,5,4)(2,7,6,8)(10,16)(14,17)(15,22)(21,23)(26,31)(30,34)(32,39)(38,40)(1,4,5,3)(2,7,6,8)(11,19)(14,17)(18,24)(21,23)(27,35)(30,34)(33,37)(38,40)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.