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