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