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