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