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