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