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