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