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