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