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