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