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