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