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