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