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