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