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