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