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