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