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