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