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