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