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