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