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