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