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