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