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