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