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