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