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