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)(11,12)(13,21)(14,18)(15,16)(17,23)(19,24)(20,22)(25,26)(27,34)(28,32)(29,31)(30,33)(35,40)(36,39)(37,38)(2,3)(6,7)(9,11,15,14)(10,12,16,18)(13,19,23,22)(17,20,21,24)(25,27,31,28)(26,32,29,34)(30,35,38,36)(33,39,37,40)(1,3,5,2)(4,7,8,6)(10,16)(11,14)(17,21)(19,22)(25,28,31,27)(26,32,29,34)(30,35,38,36)(33,40,37,39)(1,4)(2,6)(3,7)(5,8)(9,12,15,18)(10,11,16,14)(13,20,23,24)(17,19,21,22)(25,29,31,26)(27,32,28,34)(30,37,38,33)(35,39,36,40)(9,13,15,23)(10,17,16,21)(11,19,14,22)(12,20,18,24)(9,14,15,11)(10,18,16,12)(13,22,23,19)(17,24,21,20)(25,30,31,38)(26,33,29,37)(27,35,28,36)(32,39,34,40)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.