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