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