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