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