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)(27,35)(28,38)(29,32)(30,34)(31,33)(36,37)(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)(25,27,31,29)(26,32,33,35)(28,36,34,39)(30,37,38,40)(1,2,5,4)(3,6,8,7)(10,14)(15,21)(16,22)(23,24)(26,33)(28,34)(32,35)(36,39)(1,2,5,4)(3,6,8,7)(9,10)(11,15)(12,16)(13,14)(17,23)(18,21)(19,24)(20,22)(25,28,31,34)(26,30,33,38)(27,36,29,39)(32,37,35,40)(1,4,5,2)(3,7,8,6)(9,11,13,18)(10,15,14,21)(12,19,20,17)(16,24,22,23)(25,29,31,27)(26,32,33,35)(28,39,34,36)(30,37,38,40)(9,12,13,20)(10,16,14,22)(11,17,18,19)(15,23,21,24)(25,30)(26,34)(27,37)(28,33)(29,40)(31,38)(32,39)(35,36)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.