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