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