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