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