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