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