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)(11,17,12,14)(13,21,23,18)(19,22,20,24)(28,36)(32,37)(34,40)(38,39)(3,7)(5,8)(10,16)(11,12)(18,21)(19,20)(25,26)(27,31)(28,37)(29,33)(30,35)(32,36)(34,38)(39,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,11,15,12)(10,14,16,17)(13,19,23,20)(18,22,21,24)(25,27)(26,30)(28,34)(29,35)(31,33)(32,38)(36,40)(37,39)(1,3,4,7)(2,5,6,8)(9,12,15,11)(10,17,16,14)(13,20,23,19)(18,24,21,22)(25,27)(26,31)(28,34)(29,35)(30,33)(32,39)(36,40)(37,38)(1,2)(3,5)(4,6)(7,8)(9,13,15,23)(10,18,16,21)(11,19,12,20)(14,22,17,24)(25,28)(26,32)(27,34)(29,36)(30,38)(31,39)(33,37)(35,40)(9,14,15,17)(10,11,16,12)(13,22,23,24)(18,19,21,20)(25,26)(27,30)(28,32)(29,33)(31,35)(34,38)(36,37)(39,40)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.