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)(11,16)(12,17)(13,26)(14,18)(15,19)(20,37)(21,31)(22,39)(23,30)(24,33)(25,34)(27,40)(28,35)(29,36)(32,38) involution — undirected(1,2)(3,7)(4,6)(5,8)(9,11,15,13)(10,16,19,26)(12,22)(14,21,29,27)(17,32)(18,31,36,40)(20,28)(23,25)(24,38)(30,35)(33,39)(34,37)(2,6)(3,4)(7,8)(9,12)(10,17)(11,20)(13,23)(14,28)(15,24)(16,30)(18,35)(19,33)(21,38)(22,27)(25,29)(26,37)(31,39)(32,40)(34,36) involution — undirected(1,3,5,4)(2,7,8,6)(9,13,15,11)(10,16,19,26)(12,23,24,20)(14,27,29,21)(17,30,33,37)(18,31,36,40)(22,25,38,28)(32,35,39,34)A 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.