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