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