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