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