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