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