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