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