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