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