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