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