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