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