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