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