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