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