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