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