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