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