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