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