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