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