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