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