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