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