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