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