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