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