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