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