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