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