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