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