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