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