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