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