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