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