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