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