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