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