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