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