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