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