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