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