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