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