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