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