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