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