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