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