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