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