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