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