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