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