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