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