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