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