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