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