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