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