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