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