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