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