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