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