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