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