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