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