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