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