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)(11,17)(12,20)(13,14)(15,18)(16,21)(19,22)(23,24)(25,26,30,34)(27,35,36,31)(28,32,38,39)(29,33,37,40)(1,2,6,8)(3,5,7,4)(10,14)(15,17)(16,20)(22,23)(27,36)(29,37)(31,35)(33,40)(1,3,6,7)(2,4,8,5)(10,14)(11,18)(12,21)(22,23)(25,27,30,36)(26,31,34,35)(28,29,38,37)(32,40,39,33)(1,4,6,5)(2,3,8,7)(9,11)(10,15)(12,19)(13,18)(14,17)(16,22)(20,23)(21,24)(25,28,30,38)(26,32,34,39)(27,37,36,29)(31,33,35,40)(1,2)(3,4)(5,7)(6,8)(9,10)(11,17)(12,16)(13,14)(15,18)(19,23)(20,21)(22,24)(25,29,30,37)(26,33,34,40)(27,28,36,38)(31,39,35,32)(1,5,6,4)(2,7,8,3)(9,12,13,21)(10,16,14,20)(11,19,18,24)(15,22,17,23)(25,26)(27,35)(28,32)(29,33)(30,34)(31,36)(37,40)(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.