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