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