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