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