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