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