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