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