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