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