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