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