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