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