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)(11,13,18,16)(12,20,23,17)(19,24,21,22)(25,26,31,34)(27,30,33,39)(28,29,32,38)(35,36,37,40)(3,7)(5,8)(10,15)(11,18)(17,20)(19,21)(25,27)(26,30)(28,35)(29,36)(31,33)(32,37)(34,39)(38,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(10,15)(13,16)(17,20)(22,24)(27,33)(30,39)(35,37)(36,40) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,11,14,18)(10,16,15,13)(12,21,23,19)(17,22,20,24)(25,28)(26,29)(27,35)(30,36)(31,32)(33,37)(34,38)(39,40)(1,2)(3,5)(4,6)(7,8)(9,12,14,23)(10,17,15,20)(11,19,18,21)(13,22,16,24)(25,29)(26,32)(27,36)(28,34)(30,37)(31,38)(33,40)(35,39)(9,13,14,16)(10,18,15,11)(12,22,23,24)(17,21,20,19)(25,30,31,39)(26,33,34,27)(28,36,32,40)(29,37,38,35)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.