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