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