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