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