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