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