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