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