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