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