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)(25,26,30,28)(27,32,34,31)(29,36,37,33)(35,38,40,39)(1,2)(3,8)(4,5)(6,7)(10,14)(12,21)(15,17)(19,24)(27,34)(29,37)(31,32)(33,36) involution — undirected(2,7)(3,4)(10,14)(11,18)(16,20)(19,24)(25,27,30,34)(26,31,28,32)(29,35,37,40)(33,38,36,39)(1,3,6,4)(2,8,7,5)(9,11)(10,15)(12,19)(13,18)(14,17)(16,22)(20,23)(21,24)(25,28,30,26)(27,31,34,32)(29,36,37,33)(35,38,40,39)(1,4,6,3)(2,5,7,8)(9,10)(11,15)(12,16)(13,14)(17,18)(19,22)(20,21)(23,24)(25,27)(26,32)(28,31)(29,35)(30,34)(33,39)(36,38)(37,40)(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)(26,33)(27,35)(28,36)(30,37)(31,38)(32,39)(34,40)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.