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