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