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