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)(11,19,20,16)(12,17,21,24)(13,22,23,18)(25,26)(27,29)(28,31)(30,36)(32,34)(33,38)(35,39)(37,40)(1,3,6,5)(2,7,8,4)(10,15)(12,21)(16,19)(18,22)(25,27)(26,32)(28,29)(30,35)(31,34)(33,39)(36,37)(38,40)(10,15)(11,20)(17,24)(18,22)(26,28)(27,34)(33,36)(35,40) involution — undirected(1,4,6,7)(2,5,8,3)(9,11)(10,16)(12,22)(13,17)(14,20)(15,19)(18,21)(23,24)(25,28,31,26)(27,29,34,32)(30,36,38,33)(35,37,40,39)(1,5,6,3)(2,7,8,4)(9,12)(10,17)(11,18)(13,19)(14,21)(15,24)(16,23)(20,22)(25,29)(26,27)(28,34)(30,37)(31,32)(33,35)(36,40)(38,39)(1,2)(3,7)(4,5)(6,8)(9,13,14,23)(10,18,15,22)(11,17,20,24)(12,16,21,19)(25,30)(26,33)(27,35)(28,36)(29,37)(31,38)(32,39)(34,40)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.