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