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