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