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