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