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