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)(11,19)(12,18)(13,16)(14,20)(15,17)(21,24)(22,23)(25,26,31,35)(27,32,30,34)(28,33,39,29)(36,38,37,40)(2,5)(6,7)(9,11,15,13)(10,16,17,19)(12,23,20,21)(14,22,18,24)(25,27,31,30)(26,32,35,34)(28,37,39,36)(29,38,33,40)(1,2)(3,6)(4,5)(7,8)(10,17)(12,20)(16,19)(21,23)(25,28,31,39)(26,33,35,29)(27,36,30,37)(32,38,34,40)(1,3,4,8)(2,6,5,7)(9,12)(10,18)(11,21)(13,23)(14,17)(15,20)(16,22)(19,24)(25,28)(26,29)(27,37)(30,36)(31,39)(32,38)(33,35)(34,40)(9,13,15,11)(10,19,17,16)(12,23,20,21)(14,22,18,24)(25,29)(26,28)(27,38)(30,40)(31,33)(32,37)(34,36)(35,39)(9,14,15,18)(10,20,17,12)(11,22,13,24)(16,21,19,23)(25,30,31,27)(26,34,35,32)(28,37,39,36)(29,38,33,40)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.