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