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