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