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