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