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)(11,14)(12,17)(13,16)(15,20)(18,22)(19,24)(21,23)(25,26)(27,37)(28,34)(29,40)(30,36)(31,33)(32,39)(35,38)(1,2)(3,6)(4,7)(5,8)(9,10,14,11)(12,15,20,17)(13,16,22,18)(19,23,21,24)(25,27)(26,32)(28,35)(29,34)(30,38)(31,39)(33,37)(36,40)(1,3,5,4)(2,6,8,7)(10,11)(15,17)(16,18)(23,24)(26,33)(28,36)(32,37)(35,40)(9,11,14,10)(12,17,20,15)(13,18,22,16)(19,24,21,23)(25,28,31,36)(26,34,33,30)(27,35,39,40)(29,37,38,32)(1,3,5,4)(2,6,8,7)(9,12,14,20)(10,15,11,17)(13,21,22,19)(16,24,18,23)(25,29,31,38)(26,35,33,40)(27,34,39,30)(28,37,36,32)(1,4,5,3)(2,7,8,6)(9,13,14,22)(10,16,11,18)(12,19,20,21)(15,23,17,24)(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.