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