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