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